For example, planar motors are familiar from the electronics industry where, when manufacturing integrated circuits, semiconductor wafers must be positioned with extreme accuracy in a plane, for example, in order to process the wafers photolithographically.
U.S. Pat. No. 6,188,147 describes such a planar motor, which features a planar base element having pyramid-shaped protrusions on which magnets having different directions of magnetization are mounted, so that in sum, a magnetic field perpendicular to the base element is obtained over each of the pyramids. Between the pyramids, further magnets having a magnetization parallel to the base element are arranged according to the type of a Halbach array. Such a magnet array is quite costly to produce, since a great number of magnets with very narrow dimensional tolerances are necessary, whose placement is difficult because of the strong magnetic forces.
U.S. Pat. No. 6,879,063 describes a planar motor having a simpler design with a Halbach array of magnets. In that case, the magnets are cuboidal, i.e., have the shape of a right parallelepiped, which reduces their number in comparison to the device above. Nevertheless, these magnets must also be produced with narrow tolerances, and it is necessary to cope with high magnetic forces during the installation.